title: Coverage of atypical pathogens for hospitalised patients with community-acquired pneumonia is not guided by clinical parameters.
abstract: BACKGROUND
  Although most experts recommend empirical antibiotic treatment, covering also atypical bacteria, for patients admitted to an intensive care unit (ICU), the data are not clear for patients admitted to a general ward. European guidelines recommend starting empirical treatment with a beta-lactam antibiotic with or without a macrolide, but the with/without is not clarified. We investigated whether the use of antibiotic coverage for atypical pathogens was guided by clinical parameters.
  
  
  METHODS
  We retrospectively analysed 300 patients hospitalised with community-acquired pneumonia. Four parameters for possible atypical pneumonia (age <55 years, abdominal symptoms, sodium <130 mmol/l, immunosuppression) and three for pneumonia severity (pneumonia severity index [PSI], ICU admission, pO2 <8 kPa (60 mm Hg) or O2 saturation <90%) were defined and correlated with the probability of coverage for atypical pathogens. Correlations were calculated using the chi-square test for 2 x 2 tables.
  
  
  RESULTS
  Patients younger than 55 years significantly more likely to receive coverage for atypical pathogens than older patients (odds ratio [OR] 2.68; 95% confidence interval [CI] 1.3-5.5, p = 0.009). In patients with a PSI >III the proportion receiving coverage for atypical bacteria was even smaller than in patients with less severe pneumonia (OR 0.77; 95% CI 0.60-0.99, p = 0.03), but no difference was found for PSI >IV compared with PSI ≤IV (OR = 1.03; 95% CI 0.61-1.74, p = 0.9). The other clinical parameters had no effect on antibiotic coverage: ICU admission (OR =1.39; 95% CI 0.87-2.4, p = 0.15); pO2 >8 kPa or O2-Saturation >90% (OR 1.36; 95% CI 0.85-2.17, p = 0.19); abdominal symptoms (OR 1.06; 95% CI 0.51-2.25, p = 0.88); sodium <130 mmol/l (OR 0.63; 95% CI 0.29-1.36, p = 0.2) or immunosuppression (OR 1.007; 95% CI 0.462-44, p = 1). There was also no correlation between the number of clinical parameters present and the coverage of atypical pathogens (r = 0.48). Mortality was no different between patients in whom atypical pathogens were covered compared with those with beta-lactam therapy alone (OR 1.2; 95% CI 0.66-2.25, p = 0.43).
  
  
  CONCLUSIONS
  Physicians have difficulties deciding when to cover atypical pathogens in hospitalised patients with community-acquired pneumonia. Guidelines should clarify under what circumstances combination therapy is warranted.
authors.affiliation: Kantonsspital Olten, SWITZERLAND; jpiso_ol@spital.ktso.ch.
authors.forename: Rein J
authors.initials: RJ
authors.lastname: Piso
authors.forename: Christiane
authors.initials: C
authors.lastname: Arnold
authors.forename: Stefano
authors.initials: S
authors.lastname: Bassetti
mesh_terms: D000328:Adult; D000367:Age Factors; D000368:Aged; D000900:Anti-Bacterial Agents / Q000627:therapeutic use*; D061387:Chlamydial Pneumonia / Q000188:drug therapy; D017291:Clarithromycin / Q000627:therapeutic use; D017714:Community-Acquired Infections / Q000188:drug therapy* / Q000276:immunology; D004359:Drug Therapy, Combination / Q000706:statistics & numerical data; D019983:Guideline Adherence / Q000706:statistics & numerical data*; D006760:Hospitalization; D006801:Humans; D016867:Immunocompromised Host; D007877:Legionnaires' Disease / Q000188:drug therapy; D018942:Macrolides / Q000627:therapeutic use*; D008297:Male; D008875:Middle Aged; D016017:Odds Ratio; D018410:Pneumonia, Bacterial / Q000188:drug therapy* / Q000276:immunology; D011019:Pneumonia, Mycoplasma / Q000188:drug therapy; D011018:Pneumonia, Pneumococcal / Q000188:drug therapy; D017410:Practice Guidelines as Topic; D010818:Practice Patterns, Physicians' / Q000706:statistics & numerical data; D012189:Retrospective Studies; D012720:Severity of Illness Index; D047090:beta-Lactams / Q000627:therapeutic use*
chemical_list: D000900:Anti-Bacterial Agents; D018942:Macrolides; D047090:beta-Lactams; D017291:Clarithromycin